Tree species suitable for tree-ring dating
Identification of Wood Species
As previously stated, oak has the greatest potential for dating in England, which fortunately coincides with the fact that in the past it was the most commonly used wood. Identifying the different tree species is more difficult than when they are not living trees. Oak is also relatively easy wood to identify, but difficulties with other species may occur.
Colour alone is a poor guide to identifying a wood species as staining has long been used to make one type of wood look like another. Surfaces coated with either varnish or wax can often fill the pores as well as change the colour of the wood and make identification difficult.
A simple reference guide for the identification of tree species from the wood alone follows. The guide is purely intended to help you identify the various species of wood which commonly are found in domestic and architectural use in Britain. Please note that you do not have to identify any wood to a species before you can send it for dating, the identification process will be completed by Tree-Ring Services.
The 6 main species for dating and their identifying characteristics
|Oak: Large pores, easily seen at normal reading distance, are noticeably concentrated in the earlywood. Large prominent rays (some finer between). Many pores between large rays and finer rays between pores. Smaller pores of late wood may form a radial "flames" pattern.|
|Elm: Large pores with an abrupt change between earlywood and latewood, and wavy parallel lines of medium pores in the latewood. Fine and medium rays, (just visible to the naked eye when the wood is wet). One or two pores between rays. Wood dull yellow, brown or pink, and coarse grained.|
|Ash: Large to medium pores, oval in shape. Earlywood gradually merges to latewood. Pores occur singularly or in radial chains especially in latewood (2-5 in a chain). Fine rays with one or two pores between rays.|
|Beech: Pores are small to medium and may not be visible to the naked eye. Pores gradually decrease in size and number outward within each ring. Mixture of fine (hard to see) and large rays with more than six pores between large rays. Wood white or pale yellow with distinctive red-brown flecks on the longitudinal face (i.e., not on the end-grain).|
|Pine: Pores normally visible with a hand-lens. Rings distinct with an abrupt transition between the dark latewood and pale earlywood. Soft wood, does not resist fingernail pressure. Colour:- White, yellow or red-brown.|
|Yew: Pores not visible. Prominent rings defined by dark latewood. Hard wood, resists fingernail pressure. Colour:- red/brown (often yellow near bark).|
The illustrations show the microscopic structure of the woods. Rays radiate out from the centre of the tree and these may be narrow or wide depending of the tree species. The number of pores sandwiched between the rays, (counting the number of pores encountered along any line at right-angles to the rays), varies between tree species. Pores may also be singular (discrete from each other) as seen in oak or joined into short radial chains (where a number of pores are closely pressed together in a line approximately parallel to the rays) as can be seen in ash.
If difficulties occur in species identification there are usually books available in your local Library which can help in the identification of wood through various features. Please note that even in a single species such as oak, the pores in the earlywood can vary considerably in general number, size and distribution, as can the average ring-widths. Pine and spruce may be confused, though spruce shows a gradual transition between latewood and earlywood, also pine may have a resinous smell that spruce does not.